A semiconductor light emitting diode (LED) is a type of semiconductor device which converts electricity into an infrared ray or light using properties of compound semiconductors to transmit and receive a signal or to be used as a light source.
Due to physical and chemical properties, group III-V nitride semiconductors are in the spotlight as a core material of light emitting devices such as LEDs and laser diodes (LDs).
Since LEDs or LDs do not include environmentally harmful materials such as mercury (Hg) used for existing lighting devices such as incandescent lamps and fluorescent lamps, LEDs or LDs have excellent eco-friendliness, have a long life, and consume low power, thereby replacing existing light sources.
Particularly, such light emitting devices have been expanding their application range in various fields such as headlights for vehicle and flashlights. It is necessary for light emitting apparatuses including LEDs to provide excellent light extraction efficiency and a radiant heat effect and to be reduced in size and weight.
Particularly, existing light emitting apparatuses focus or collimate excited light emitted from a light emitting device using an optical system before converting a wavelength of the excited light. Here, due to properties of the optical system, when an optical path becomes longer, a light emitting apparatus may become sensitive to a tolerance and may become mechanically complicated.
Also, when a light emitting apparatus is applied to a vehicle, it is necessary to be designed strong to withstand vibrations and the like. However, due to a complicated structure of an optical system, existing light emitting apparatuses are mechanically unstable.